The present disclosure relates to phthalocyanine pigments for use in photoreceptors, and more particularly to co-crystals of metal phthalocyanines, such as titanyl phthalocyanine, with metal free phthalocyanines.
Phthalocyanine pigments are currently utilized in a number of photoreceptors. Two pigments in use include titanyl phthalocyanine (TiOPC) and hydroxygallium phthalocyanine (HOGaPC). Both are fairly sensitive, depending on their morphology and methods utilized for their preparation A very sensitive TiOPC has a collection efficiency of about 85%, while the most sensitive HOGaPC has a collection efficiency of about 60% to about 70%.
Methods for producing and utilizing such pigments are known. In U.S. Pat. No. 4,898,799, the entire disclosure of which is incorporated herein by reference, there is disclosed, for example, the preparation of selected polymorphs of titanium phthalocyanines, and layered photoconductive members comprised of the prepared phthalocyanine composites. In U.S. Pat. No. 5,153,313, the entire disclosure of which is incorporated herein by reference, there is disclosed, for example, a process for the preparation of composites of titanyl phthalocyanines and vanadyl phthalocyanines by suspending the vanadyl phthalocyanine in a solvent mixture of trifluoroacetic acid and methylene chloride, adding titanyl phthalocyanine to the stirring mixture, and thereafter precipitating the desired titanyl phthalocyanine and vanadyl phthalocyanine composite. The resulting phthalocyanine composite may be utilized as a pigment for a photoreceptor.
Pigments having excellent photosensitivity, processes for their preparation, and their use in forming photoreceptors remain desirable.